Batch parsing of inline scripts/stylesheets

[MegaCorn]

Before: html5ever produces tokens for each line of inline content
After: html5ever batchs inline contents until encounter '<', which represents endtag in most cases
Fixes: servo/servo#34502

[simonwuelker]

html5ever emits the line number for each token it parses. I this change will break the line counting, because we no longer hit

html5ever/html5ever/src/tokenizer/mod.rs

Lines 258 to 260 in a7c9d98

	if c == '\n' {
	self.current_line.set(self.current_line.get() + 1);
	}

for each newline in the input data. That's probably why we interrupt the tokenizer when we see a newline in the first place.

I'd like to get rid of the line count at some point, because it also has a significant performance overhead in other places (#601 (comment)), but I have not investigated the implications.

[jdm]

The line count is important for providing useful error information for CSS and JS errors/warnings in inline style/script blocks.

[jdm]

Perhaps there is some way to increase the line number by the number of \n characters present in the batched results after leaving the raw text state or something like that?